Cardiac pacing systems typically include a pacemaker and one or more leads, which are placed inside the body of a patient. The pacemaker includes a power source and circuitry configured to send timed electrical pulses to the lead. The lead carries the electrical pulse to the heart to initiate a heartbeat, and transmits information about the heart's electrical activity to the pacemaker. The lead can include a fixation mechanism that holds the lead to the cardiac tissue. In some cases, a lead is inserted through a vein or artery (collectively vasculature) and guided to the heart where it is attached. In other instances, a lead is attached to the outside of the heart. During its time in the body, tissue can attach to the lead in the form of lesions, adhesions or scar tissue, or tissue can encase a lead. In addition, the lead and/or tissue can become attached to the vasculature wall. At times, leads may be removed from patients for numerous reasons, including but not limited to, infections, lead age, and lead malfunction. Accordingly, removal or extraction of the lead may present associated complications.
Current lead extraction techniques include mechanical traction, mechanical devices, and laser devices. Mechanical traction can be accomplished by inserting a locking stylet into the hollow portion of the lead and then pulling the lead to remove it. An example of such a lead locking device is described and illustrated in U.S. Pat. No. 6,167,315 to Coe et al., which is hereby incorporated herein by reference in its entirety for all that it teaches and for all purposes. In some cases, dilating telescopic sheaths may also be used to strip away the scar tissue adhering the lead to the body. Examples of a such devices and methods used to extract leads is described and illustrated in United States Patent Publication No. 2008/0154293 to Taylor, which is hereby incorporated herein by reference in its entirety for all that it teaches and for all purposes.
Dilation techniques typically involve pushing tissue away from the lead when the sheath is pushed longitudinally along the lead. However, this pushing technique may be difficult to implement, particularly when the lead has a tortuous path or curvature because the requisite longitudinal forces to extract the tissue from the lead in under these circumstances increase. The longitudinal forces also may require heavy counter forces on the lead, which may result in lead breakage.
Some mechanical sheaths have proposed trigger mechanisms for extending a blade from a sheath. At least some of these devices, however, involve complicated activation mechanisms and may not be well suited for negotiating the tortuous paths that exist in certain vascular or physiological environments.
Laser devices typically employ laser energy to cut the scar tissue away from the lead thus allowing for removal. Examples of such laser devices and systems are described and illustrated in U.S. Pat. Nos. 5,383,199 and 5,824,026 and 5,916,210 and 6,228,076 and 6,290,668 all of which are hereby incorporated herein by reference in their entirety for all that they teach and for all purposes.
Further complicating lead removal is the fact that in some cases, the leads may be located in, and/or attached to, the body of a patient in a structurally-weak portion of the vasculature. For instance, typical leads in a human may pass through the innominate vein, past the superior vena cava (“SVC”), and into the right atrium of the heart. A majority of tissue growth can occur along the SVC and other locations along the innominate vein where the leads make contact with the vein walls. However, tissue growth can also occur at locations within a patient where the leads make contact with arterials or other areas of the vasculature. Certain veins and arteries, and certain areas of vein and arterial walls, can be thin which can make lead removal a complicated and delicate process.